Studies will be carried out on structure-function relations in electrotonic junctions. Attention will be focused on mechanisms controlling channel conductance and developmental aspects of junction formation. The development of neuronal specificity of vestibular inputs to the Mauthner cells in the amphibian CNS will be examined with respect to the topographic distribution of afferents to regionally different components of the M-cell. Development and pathophysiological consequences of meganeurite and secondary neurite formation in pyramidal neurons, and caudate spiny neurons will be studied in feline ganglioside storage disease. The cellular basis of calyceal function in the vestibular semicircular canal system will be studied in lizards. Mechanisms of transmitter release and synaptic interaction will be studied in the Mauthner cell-giant fiber system of the hatchetfish. Other studies of interaction involve morphophysiological analysis of brain stem connections with the substantia nigra. Organizational aspects of the program will focus on the neural substrate of feeding behavior in Navanax. Studies in this program will employ combined electrophysiological, cell identification techniques and the use of electron microscopy and freeze-fracture methods.